The present invention relates to a database construction system, and more particularly, to a database construction system capable of improving the reliability of a database storing broadcast channels that can be received in each area.
The present invention also relates to a broadcast receiving system, and more particularly, to a broadcast receiving system in which an in-vehicle apparatus receiving a broadcast can set an appropriate broadcast channel in each traveling area of a vehicle.
A broadcasting system has been proposed in which a predetermined server provides information related to a broadcast channel that can be received in the place where there is a broadcast receiving apparatus. According to the broadcasting system, the broadcast receiving apparatus can easily set a receivable broadcast channel on the basis of the information received from the predetermined server without independently searching for the broadcast channel.
In order to form the broadcasting system, it is necessary to construct a database storing the broadcast channels that can be received in each area. For example, JP-A-2005-252965 discloses a technique for constructing the database storing the broadcast channels that can be received in each area.
In the technique disclosed in JP-A-2005-252965, a predetermined aggregation center receives information indicating the reception conditions related to the broadcast channels that are received by each broadcast receiving apparatus and the position of the broadcast receiving apparatus. Then, the aggregation center stores the received information so as to be associated with each area corresponding to the position included in the information, thereby constructing a database storing the broadcast channels that can be received in each area.
In the technique disclosed in JP-A-2005-252965, for example, the investigator does not need to examine the reception conditions in each area, and the aggregation center can easily construct a database storing the broadcast channels that can be received in each area only by storing the reception conditions and the position of each broadcast receiving apparatus transmitted from each broadcast receiving apparatus so as to be associated with each other.
However, the technique disclosed in JP-A-2005-252965 has a problem in that the reliability of the constructed database is low.
For example, the broadcast receiving apparatus whose broadcast receiving function does not work transmits the reception conditions indicating that a broadcast channel cannot be received to the aggregation center even though the broadcast receiving apparatus is in the area in which it can actually receive the broadcast channel. However, the aggregation center constructs a database using the incorrect reception conditions. As a result, the reliability of the database is reduced.
As such, in the technique according to the related art, the information used by the aggregation center to construct a database includes information with low reliability. As a result, the reliability of the constructed database is reduced.
In some cases, an in-vehicle broadcast receiving apparatus cannot receive the broadcast that has been received until now due to the traveling of the vehicle. A technique has been proposed in which the broadcast receiving apparatus automatically changes the broadcast channel to another broadcast channel capable of receiving a broadcast with the same content as that of the broadcast which'has been received up until now.
For example, JP-A-2002-141819 discloses a technique in which the broadcast receiving apparatus acquires information related to the electric field intensity (reception intensity) of broadcasts provided by each broadcasting station from an arbitrary broadcasting station in advance and stores the acquired information.
In the technique disclosed in JP-A-2002-141819, when the broadcast receiving apparatus cannot receive a broadcast during the traveling of the vehicle, the broadcast receiving apparatus automatically changes the broadcast channel to another broadcast channel capable of receiving a broadcast with the same content as that of the broadcast that cannot be received, on the basis of the information acquired from the broadcasting station. Therefore, the broadcast receiving apparatus can continuously receive the broadcast with the same content during the traveling of the vehicle.
However, when the technique disclosed in JP-A-2002-141819 is used, there is a concern that the in-vehicle apparatus cannot set an appropriate broadcast channel in each traveling area of the vehicle.
That is, in the technique disclosed in JP-A-2002-141819, whether the in-vehicle apparatus can set an appropriate broadcast channel in each traveling area of the vehicle depends on the reliability of the information transmitted from the broadcasting station.
When the reliability of the information transmitted from the broadcasting station is low, in some cases, the in-vehicle apparatus cannot set an appropriate broadcast channel in each traveling area of the vehicle.
Therefore, it is considered that the information of the database obtained by the technique disclosed in JP-A-2005-252965 is used instead of the information transmitted from the broadcasting station. However, in this case, the database disclosed in JP-A-2005-252965 has a problem in reliability as described above.
As such, in the related art, it is difficult for the in-vehicle apparatus to set an appropriate broadcast channel in each traveling area.